Difference Between MQTT Protocol and TCP Protocol
MQTT is an application layer protocol based on TCP, designed for the Internet of Things, supporting publish/subscribe mode and QoS level, suitable for low-bandwidth, high-latency networks; TCP is a transport layer protocol that provides reliable end-to-end data transmission without application layer semantics.
What is MQTT Protocol How it works
There are significant differences between the MQTT protocol and the TCP protocol in many aspects. The following is a detailed introduction to the two protocols that will fully and deeply explain their differences.
Protocol layer and positioning
TCP protocol
- Layer: TCP (Transmission Control Protocol) is a transport layer protocol in the OSI seven-layer model and is part of the Internet protocol suite.
- Position: TCP is a connection-oriented, reliable, byte stream-based transport layer communication protocol designed to provide end-to-end data transmission services.
MQTT protocol
- Layer: MQTT (Message Queuing Telemetry Transport) is a message protocol based on publish/subscribe mode under the ISO standard and is an application layer protocol.
- Positioning: MQTT is designed to run in remote devices and environments with limited hardware performance and poor network conditions. It is a lightweight, publish/subscribe-based instant messaging protocol.
mqtt broker server cloud free
Communication Mode and Features
TCP Protocol
- Communication Mode: TCP adopts a point-to-point communication mode, that is, a direct connection is established between the client and the server for data transmission.
- Features:
- Connection-oriented: Before data transmission, TCP needs to establish a connection first, and confirm the establishment of the connection through a three-way handshake.
- Reliability: TCP provides reliable data transmission services, and ensures the integrity and order of data through ACK confirmation and retransmission mechanisms.
- Orderliness: TCP can divide the sent data into data blocks, send them after numbering, and the receiver assembles these data blocks into complete data according to the number.
- Flow control and congestion control: TCP manages the data transmission speed through the sliding window protocol and congestion control algorithm to avoid network congestion and data loss.
TCP Protocol – How TCP/IP Works – What is TCP/IP
MQTT protocol
- Communication mode: MQTT adopts the publish/subscribe mode, that is, the publisher publishes the message to the topic, and the subscriber subscribes to the topic of interest to receive the message.
- Features:
- Lightweight: The fixed header of the MQTT message is only 2 bytes, the protocol exchange is minimized, the overhead is very small, and it is suitable for resource-constrained devices and low-bandwidth network environments.
- Publish/subscribe mode: Provides one-to-many message publishing, decouples applications, and the publisher does not need to know the specific situation of the subscriber, and the subscriber does not need to know the publisher’s information.
- Three message publishing service quality (QoS): MQTT provides three optional message publishing service quality levels: QoS 0 (at most once), QoS 1 (at least once) and QoS 2 (exactly once) to meet the message transmission requirements in different scenarios.
- High reliability: In a low-bandwidth, high-latency, and unreliable network environment, MQTT ensures reliable message transmission through functions such as message retransmission and will mechanism.
- Strong scalability: Supports a variety of types of devices and application scenarios, and can meet different business needs through the flexible combination of topics and messages.
Application scenarios and applicable environments
TCP protocol
- Application scenarios: TCP is suitable for applications that require high data transmission reliability, such as file transfer, email, web browsing, online video, etc.
- Applicable environment: TCP is suitable for environments with good network conditions and sufficient bandwidth, and can make full use of network resources to provide high-quality data transmission services.
MQTT protocol
- Application scenarios: MQTT is widely used in the field of Internet of Things, such as smart home, smart agriculture, smart transportation, industrial control, etc. In these scenarios, devices usually have limited computing power and network resources, and the network environment may be unstable.
- Applicable environment: MQTT is designed to run on remote devices and environments with limited hardware performance and poor network conditions, and can provide stable and reliable message transmission services in low-bandwidth, high-latency, and unreliable network environments.
MQTT is used in smart home IoT systems
Protocol implementation and data transmission
TCP protocol
- Protocol implementation: The implementation of the TCP protocol involves complex algorithms and mechanisms, such as three-way handshake, four-way handshake, sliding window protocol, congestion control algorithm, etc.
- Data transmission: TCP transmits data in a connection-oriented manner to ensure the integrity and order of the data. During the transmission process, TCP will segment, number, confirm and retransmit the data.
MQTT protocol
- Protocol implementation: The implementation of the MQTT protocol is relatively simple, mainly involving the publish/subscribe mechanism, message queue, QoS mechanism, etc.
- Data transmission: MQTT transmits messages through the publish/subscribe mode. The publisher publishes the message to the topic, and the subscriber subscribes to the topic of interest to receive the message. During the transmission process, MQTT will select different transmission strategies according to the QoS level to ensure the reliable transmission of the message.
mqtt broker
Protocol performance and overhead
- TCP protocol
- Performance: TCP provides high-quality data transmission services, but delays and packet loss may occur when the network conditions are poor.
- Overhead: The overhead of the TCP protocol is relatively large, including the overhead in the process of connection establishment, data confirmation and retransmission.
- MQTT protocol
- Performance: MQTT is designed for IoT environments and can provide stable and reliable message transmission services in low-bandwidth, high-latency, and unreliable network environments.
- Overhead: The MQTT protocol has a small overhead, a fixed-length header of only 2 bytes, and minimized protocol exchanges, making it suitable for resource-constrained devices and low-bandwidth network environments.
Similarities and differences between MQTT protocol and TCP protocol
The following will discuss the similarities and differences between MQTT protocol and TCP protocol in detail.
Similarities
Based on IP network:
- Both MQTT and TCP are based on IP networks for data transmission, which means that they can both run on the Internet or in a local area network.
Reliability mechanism:
- Both have a certain degree of reliability mechanism. TCP ensures reliable data transmission through mechanisms such as confirmation (ACK), retransmission, and sliding windows. MQTT provides message delivery reliability through different quality of service (QoS) levels (such as QoS 1 and QoS 2).
Wide application:
- Both MQTT and TCP are widely used protocols. As one of the basic protocols of the Internet, TCP is used in almost all scenarios that require reliable data transmission. MQTT has been widely used in the field of the Internet of Things, especially in resource-constrained devices and low-bandwidth, high-latency network environments.
What Are AI Agents Really About – MQTT for AI robot communication
Differences
Protocol Layer:
- TCP: Transport layer protocol, responsible for providing reliable, connection-oriented data transmission services between source hosts and destination hosts.
- MQTT: Application layer protocol, built on the TCP/IP protocol stack, focusing on message transmission between IoT devices.
Communication Mode:
- TCP: Point-to-point communication mode, a direct connection is established between the client and the server for data transmission.
- MQTT: Publish/Subscribe mode, the publisher publishes messages to the topic, and the subscriber subscribes to the topic of interest to receive messages. This mode decouples applications and improves the flexibility and scalability of the system.
Features and Advantages:
- TCP:
- Connection-oriented, providing reliable data transmission services.
- Suitable for applications that require high data transmission reliability, such as file transfer, email, etc.
- The overhead is relatively large, including the overhead in the process of connection establishment, data confirmation and retransmission.
- MQTT:
- Lightweight, low overhead, suitable for resource-constrained devices and low-bandwidth network environments.
- Provide three message publishing service quality levels (QoS 0, QoS 1, QoS 2) to meet the message transmission needs in different scenarios.
- Support one-to-many message publishing, easy to integrate and expand devices.
Application scenarios:
- TCP: Suitable for various applications that require reliable data transmission, such as web browsing, online video, file transfer, etc.
- MQTT: Designed for IoT environments, it is widely used in smart homes, smart agriculture, smart transportation, industrial control and other fields. In these scenarios, devices usually have limited computing power and network resources, and the network environment may be unstable.
MQTT for IoT
Message transmission mechanism:
- TCP: Transmit data in the form of byte streams, without retaining the boundaries of messages. The receiver needs to parse the data by itself to determine the boundaries and content of the message.
- MQTT: Transmission is carried out in units of messages, and each message has clear boundaries and content. This makes MQTT more flexible and convenient in message processing.
Connection Management:
- TCP: Connection management is relatively complex, and it is necessary to handle the establishment, maintenance and release of the connection.
- MQTT: Connection management is relatively simple. After the connection is established between the client and the server, messages can be transmitted through the publish/subscribe mechanism. MQTT also supports functions such as persistent sessions (Clean Session) and last will and testament messages (Last Will and Testament), which further simplifies connection management.
Summary
MQTT protocol and TCP protocol have significant differences in protocol level, communication mode, characteristics and advantages, application scenarios and message transmission mechanism.
TCP, as a transport layer protocol, provides reliable and connection-oriented data transmission services, which is suitable for various applications that require reliable data transmission.
MQTT, as an application layer protocol, is designed for IoT environments. It has the characteristics of lightweight, low overhead, publish/subscribe mode, etc., and is suitable for resource-constrained devices and low-bandwidth, high-latency network environments.
In practical applications, the appropriate protocol should be selected for data transmission based on specific needs and network environment.
MQTT protocol for ESP32
About IoT Cloud Platform
IOT Cloud Platform (blog.iotcloudplatform.com) focuses on cutting-edge technology products and IoT project knowledge such as WiFi modules, IoT programming, sensor programming, smart home sensors, home smoke alarms, smart gateways, smart homes, smart communities, smart nursing homes, smart cities, RFID, lora devices, IoT systems, IoT modules, IoT solutions, lithium batteries, etc.
FAQs
The following are common questions and answers about the difference between MQTT protocol and TCP protocol:
MQTT: A lightweight message transmission protocol based on TCP, designed for the Internet of Things (IoT), using a publish/subscribe model, and supporting low-bandwidth, high-latency or unreliable network environments.
TCP: Transmission Control Protocol, a connection-oriented reliable transmission protocol that ensures data is transmitted in order and without loss, and is one of the basic protocols for Internet communication.
Protocol level:
MQTT is an application layer protocol, implemented on the TCP transport layer.
TCP is a transport layer protocol, responsible for end-to-end data transmission.
Functional positioning:
MQTT provides a message publish/subscribe mechanism and supports QoS (quality of service) levels.
TCP only guarantees reliable data transmission and has no message semantics.
Resource consumption:
MQTT has a small header overhead (only 2 bytes of fixed header), which is suitable for low-bandwidth devices.
TCP has a large header overhead (20 bytes) and needs to maintain a connection state.
MQTT:
IoT devices (such as sensors, smart homes).
Mobile application message push.
Remote monitoring and control systems.
TCP:
File transfer (such as HTTP, FTP).
Database communication.
Video/audio streaming (needs to be combined with application layer protocols).
MQTT:
Balance reliability and efficiency through QoS mechanism (e.g. QoS 0 sacrifices reliability for low latency).
Supports Last Will and Testament and session persistence.
TCP:
Ensures reliability through three-way handshake, ACK and retransmission mechanism.
No built-in message retry or offline storage function.
MQTT:
Supports topic hierarchy (e.g. home/livingroom/temperature).
Data synchronization can be optimized through retained messages.
TCP:
Need to combine application layer protocols (e.g. MQTT, HTTP) to achieve extended functions.
Strong versatility, but lacks IoT-specific optimization.
Choose MQTT:
Limited device resources (e.g. memory, bandwidth).
One-to-many communication or dynamic topic subscription is required.
Unstable network environment (such as wireless sensor networks).
Choose TCP:
Need to directly control the transport layer logic (such as custom protocols).
The application layer has implemented a complete protocol (such as HTTP over TCP).
High reliability requirements and sufficient bandwidth.
No. MQTT relies on TCP as the transport layer and is suitable for specific scenarios (such as the Internet of Things), while TCP is a general transport protocol. The two belong to different levels and need to be used in combination according to needs.
TCP ensures the reliability of the transport layer (no data loss or duplication), while MQTT’s QoS defines the application layer message delivery semantics (such as whether confirmation is required). The two complement each other.
